I/GCSE Biology - The Digestive System (2)

Have you read the previous of digestive system part 1? We will move on talking about the roles of enzymes and alimentary canal in this post! 😁

• Carbohydrase digest carbohydrates, e.g. Amylase digests starch to simple sugars
• Proteases digest proteins to amino acids
• Lipases digest fats to fatty acids and glycerol

In I/GCSE Biology, it's important to memorize how bile functions in the exam!

1. Bile is added in the small intestine to neutralise stomach acid.
2. This means that the enzymes in the stomach can work at their optimum pH.
3. Bile also emulsifies (break up large drops of fat into smaller droplets that remain mixed in a watery liquid) fats so that there is a greater surface area for lipases to work on.

a muscular tube running from the mouth to the anus.

• One villus / many villi.
• The large capillary network carries absorbed molcules away quickly
• maintain a steep concentration gradient for diffusion.
• Millions of villi means an increased surface area.
• The surface is formed from a single layer of cells making diffusion easier.

Last but not least, you should know the following points in I/GCSE Biology as well!

Functional foods are food that claim to make you healthier when you eat them.

Probiotics:

• Contain friendly bacteria
• Little scientific evidence to support that it improves your digestive and immune system

Prebiotics:

• Contain high levels of oligosaccharides
• Scientific evidence of them improving health by reducing the risk of diarrhoea

Plant stanol esters:

• Reduce the amount of chlolesterol absorbed from digested food
• May reduce risk of heart disease

And we're done with this topic! Well Done!

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Drafted by Alyssa (Biology)

References:

1. "B2 - Enzymes", https://images.slideplayer.com/12/3396173/slides/slide_6.jpg
2. "What Is the Function of Bile?", https://images.medicinenet.com/images/article/main_image/what-is-the-function-of-bile.jpg
3. "gastrointestinal tract", https://cdn.britannica.com/39/8039-050-84745FFB/human-digestive-system-front.jpg
4. "Villi in the small intestine". Photo from the internet.
5. "Probiotics and Prebiotics as Functional Foods: State of the Art | Bentham Science". Photo from the internet.